This invention relates to electronically processed sound. More particularly, this invention relates to a method and apparatus for enhancing the quality, clarity, presence, intelligibility and other characteristics of electronically processed sound. The invention is especially useful with, but not exclusively limited to, sound recording equipment, sound reproduction equipment, sound reinforcement equipment, sound analysis equipment and sound transmission equipment.
In U.S. Pat. No. 2,866,849 there is disclosed an apparatus for improving sounds of music and speech in which an audio signal is split into two signal paths and the signal in one path is passed successively through an amplifier, a 3KC high pass filter, a harmonic producer, a 6KC high pass filter and an amplifier and is then combined, either electrically or acoustically, with the signal in the other path.
In U.S. Pat. No. 2,852,604, there is disclosed a sound reproduction apparatus in which a monaural electrical signal is divided into two paths and the signal in one path is passed through a time delay mechanism. The two signals are then converted to sound through separate speakers.
In U.S. Pat. No. 3,219,757, there is disclosed a sound reproduction apparatus in which a monaural electrical signal is divided into two paths and the signal in one path is passed through a non-linear frequency dependent phase delay circuit. The two signals are then mixed in two different ways. One of the mixed signals is converted to sound through one speaker and the other mixed signal is converted to sound through another speaker.
In U.S. Pat. No. 3,560,656 there is disclosed a sound reproduction apparatus in which a monaural electrical signal is divided into two signal paths and the signal in one path is passed through a phase changing circuit. The two signals are then converted to sound through separate spaced apart speakers, with the sound emerging from both speakers having the same amplitude.
Other examples of electronic sound processing apparatus pertienent in one way or another to this invention may be found in U.S. Pat. Nos. 2,866,849; 2,953,644; 3,127,476; 3,591,699; 3,723,633; 3,745,254; 3,819,861; 3,828,133; and 3,890,466.